Anti-icing agent



United States Patent Oifice 3,140,162 Patented July 7, 1964 3,140,162ANTI-ICING AGENT Donald A. Maxwell and Ben N. Stuckey, Kingsport,

Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., acorporation of New Jersey No Drawing. Filed Oct. 18, 1961, Ser. No.145,973 4 Claims. (Cl. 44-66) This invention relates to additives forreducing ice formation temperature, and for inhibiting carburetor icingtendency, in hydrocarbon fuels containing entrained water. Moreparticularly the invention relates to hydrocarbon fuels containing minorportions of 2,2,4-trimethyl-1,3-pentanediol-dipelargonate.

A problem with modern aviation fuels, particularly jet engine fuels, hasbeen the formation of ice crystals in the fuel at extremely lowtemperatures. At low temperatures encountered in high altitude flying,water entrained even in small amounts in the liquid fuel will form icecrystals that tend to accumulate, restricting fuel lines and fuel tankdrains. The temperature at which these crystals begin to form in thefuel is called the ice formation temperature.

An object of this invention, therefore, is to provide an additive toinhibit ice formation in aviation fuels at the low temperaturesencountered under extreme flying conditions. Broadly, an object is toprovide an additive for reducing ice formation temperature ofhydrocarbon liquids containing entrained water. Particularly, an objectis to provide an additive which can reduce the ice formation temperaturein water saturated jet engine fuel at least to 65 F., a temperature nearthe extreme of low temperatures encountered in high altitude flying.Another object is to provide an additive to inhibit carburetor icingtendency in gasolines containing small amounts of entrained water.Another object is to provide fuels containing this additive.

We have found that the ice formation temperature of water saturatedhydrocarbon liquids especially jet fuels can be lowered by addition of asmall amount of 2,2,4- trimethyl-l,3-pentanediol-dipelargonate to thehydrocarbon liquid. To be suitable as an additive for depressing the iceformation temperature of jet fuels or as an additive for inhibitingcarburetor icing tendency in gasolines, the material must be able toreduce ice formation temperature to -6S F., or to inhibit carburetoricing tendency, without imparting corrosive or other deleteriousproperties to the fuel and without deleterious effect on its function asa fuel. We have found that the additive mentioned above is suitable inthese respects when added in small amounts. In one preferred embodimentof the invention a jet fuel having an ice formation temperature of -65F., or lower consists of a hydrocarbon jet fuel, for instance JP-4 jetfuel, to which has been added a small amount of2,2,4-trimethyl-1,3-pentanedioldipelargonate. While We have beenconcerned primarily with the problem of reducing ice formationtemperatures in jet fuels, it is to be understood that the additive ofthe invention may be added to other liquid hydrocarbon fuels such asgasoline or diesel fuel to perform the function of reducing iceformation temperature.

To determine the ice formation temperature of fuels containing theadditive of the invention we have employed the apparatus of ASTM TestD97-57 for determining pour point. The procedure of that test ismodilied to determine ice formation temperature. The temperature of thesample is reduced to the temperature at which formation of ice crystalsis first observed in the fuel sample.

The amount of additive needed to lower ice formation temperature willdepend upon a number of factors including the desired depression of iceformation temperature and the characteristics of the fuel being treated;the amount will have to be determined for each particular application.For the JP-4 jet fuel, which we have selected for testing, from 0.10 to0.25 volume percent of the additive of the invention was sufficient toreduce ice formation temperature to F. The following example illustratesthe invention by reference to a preferred embodiment.

Example I A sample of JP-4 jet fuel Was saturated with water. Thesaturated sample contained ppm. plus 2 ml. of water per gallon of fuel.A control portion of this sample was tested by the modified proceduredescribed above to determine ice formation temperature. The temperaturewas lowered until formation of ice crystals in the sample was observed.This occurred at -54 F. To another portion of the saturated sample wasadded 0.10 volume percent of2,2,4-trimethyl-1,3-pentanedioldipelargonate. This portion was tested bythe same method. The ice formation temperature was 68 F.

Depression of ice formation temperature of JP-4 jet fuels will occurwhen an amount of from about 0.01 to about 0.5% by weight of theadditive of the invention is added to the fuel. The degree of depressionwill increase, though not necessarily proportionally, as the amount ofadditive present is increased within this range. For other fuels therange of elfective addition may be greater.

An additional and somewhat related function has been discovered for2,2,4-trimethyl-1,3-pentanediol-dipelargonate as an additive forhydrocarbon fuels. When added to gasolines in small amounts of about 15%by volume, 2,2,4-trimethyl-1,3-pentanediol-dipelargonate will not onlyreduce ice formation temperature but will also inhibit carburetor icingtendency in the motor fuel. Carburetor icing is caused when gasoline isvaporized in the carburetor. The reduction of temperature caused byvaporization of the gasoline causes Water entrained in the gasoline tocondense and freeze in the carburetor. To inhibit this carburetor-icingeffect in gasolines, a greater amount of additive is required than isusually necessary to obtain effective depression of ice formationtemperature. When added to a gasoline in an amount of about 2% byvolume, 2,2,4-trimethyl-1,3-pentanediol-dipelargonate was found to causeless carburetor icing than did a sample of the same gasoline without anadditive. The additive may be added to hydrocarbon fuels by simplymixing the fuel and the additive together.

The hydrocarbon liquids contemplated by this invention are thosepetroleum fractions ordinarily used as fuels in internal combustionpiston and jet engines. Such fuels seldom have a distillation end pointabove 600- 650 F. and are low-viscosity liquids unsuitable for lubricantuses. JP-4 fuel and some other jet engine fuels among the kindcontemplated are described in Military Specification Mill5624D.Gasolines for use in automotive and aircraft piston engines aredescribed in numerous available literature references.

The additive of this invention may be prepared by reacting2,2,4-trirnethylpentanediol and 1,3-pelargonic acid by the methoddescribed in US. Patent No. 2,798,- 083 to Bell and Lappin, patentedJuly 2, 1957.

The invention has been described by reference to specific examples, itbeing understood that variations and modifications can be made Withinthe spirit and scope of the appended claims.

We claim:

1. A hydrocarbon fuel comprising a major portion of hydrocarbon liquidhaving a distillation end point below 650 F. and at least 0.01 volumepercent based on the hydrocarbon volume of2,2,4-trimethyl-1,3-pentanedioldipelargonate.

2. A hydrocarbon fuel comprising a major portion of a hydrocarbonjet-engine fuel and from about 0.01 to about 0.50 volume percent of2,2,4-trimethyl-1,3-pentanediol-dipelargonate.

3. A gasoline containing from about 1 to about 5 percent by Weight of2,2,4-trimethyl-l,3-pentanediol-dipelargonate.

4. A hydrocarbon fuel consisting essentially of gasoline and about 2.0%by volume of 2,2,4-trimethyl-l,3-pen- 1O tanediol-dipelargonate.

References Cited in the file of this patent UNITED STATES PATENTS Bellet a1. July 2, 1957 Moore Nov. 22, 1960

1. A HYDROCARBON FUEL COMPRISING A MAJOR PORTION OF HYDROCARBON LIQUIDHAVING A DISTILLATION END POINT BELOW 650*F. AND AT LEAST 0.01 VOLUMEPERCENT BASED ON THE HYDROCARBON VOLUME OF2,2,4-TRIMETHYL-1,3-PENTANEDIOLDIPELARGONATE.